Friday, November 20, 2009

Algebra 1A & 1B (Friday)

Before you get started on your MyMathLab work, check out these Carbon/Nitrogen Ratios. At the top it says that a 30:1 ratio is best for compost, in other words, 30 parts carbon to every 1 part nitrogen. We'll be composting kitchen scraps, and notice that "kitchen scraps" near the bottom is 10-20% carbon and 1-2% nitrogen (too little carbon).

Let's assume our kitchen scraps going into our compost will be around 15% carbon and 1.5% nitrogen. In other words, for 100 grams of scraps, 15 grams will be carbon and 1.5 grams will be nitrogen.

The ecology class identified nonlegume hay, wheat straw, and leaves as possible sources of carbon, to balance out the ratio. If we use hay, and assume it has 40% carbon and 1% nitrogen, we can write a formula to determine how many grams of hay to add to each 100 grams of scraps to get the right 30:1 ratio.

The formula ends up looking like this: (100 x 15% + H x 40%) / (100 x 1.5% + H x 1%) = 30/1 = 30
(H is grams of hay, 100 is grams of kitchen scraps, and carbon is on top, nitrogen on the bottom)

Use this formula to find how many grams of hay should be added (round to the nearest gram). The first step will be to multiply everything by the denominator (100 x 1.5% + H x 1%) Turn in your work and results to me, and we'll use them for the compost!

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